Ejectors, sometimes called gas or steam ejectors or venturi ejectors, are generally known in the art. They are commonly used to maintain a vacuum or to compress a gas. The advantage of the ejector over conventional mechanical pumps, such as piston pumps or compressors and diaphragm pumps, is that ejectors have no moving parts and are generally robust (subject to filtering the gas streams to reduce pitting and corrosion). Typically ejectors are subsonic, as supersonic ejectors tend to produce a low pressure exit stream. Additionally supersonic ejectors are generally more sensitive to design/construction parameters for proper operation.
An ejector typically includes an expansion nozzle port through which a motive gas enters the ejector via an inlet port. The gas is expanded to a lower pressure as it passes through a constricted throat section of the expansion nozzle. Generally there is a suction port opening into an enclosed chamber about the expansion nozzle through which the gas to be captured is drawn into the ejector by the pressure differential. Then downstream of the expander there is generally a diffuser section having an inlet, a throat section, and a diverging discharge section.
Conventional subsonic ejectors are commonly used to maintain a vacuum on a system such as disclosed in the following patents: U.S. Pat. No. 5,380,822 discloses the use of a gas, typically steam, ejector to maintain a lower pressure in the later stages of a falling strand devolatilizer than in the down stream condenser to prevent water from freezing; U.S. Pat. No. 6,855,248 teaches the use of a steam ejector to maintain a vacuum on a processing column; U.S. Pat. No. 6,330,821 teaches the use of a gas ejector to maintain a vacuum on a part being tested; U.S. Pat. No. 4,194,924 teaches distilling a carrier solvent and JP-4 in a heated vacuum column in which the vacuum is provided by a gas (steam) ejector; and U.S. Pat. No. 4,834,343 teaches a non flooded treatment column including a venturi device within the top of the column to re-disperse the gas beneath the fluid level. Each of the aforementioned patents is hereby incorporated by reference in their entirety into the present disclosure, to the extent that the aforementioned patents are not inconsistent with the present disclosure.
However, one challenge with the prior art disclosures is the packaging of the ejector systems. More particularly, Applicants have licensed the technology embodied in U.S. patent application Ser. No. 11/809,342 entitled Tandem Supersonic Ejectors (the “'342 application”), which is hereby incorporated by reference in its entirety into the present application. However, in implementing the technology of the '342 application, Applicants have encountered several challenges associated with the size and packaging of the tandem supersonic ejectors. As with the other prior art ejectors noted above, the '342 tandem ejector system is bulky and not desirable for field implementation. As such, there is a need for an efficient, compact, and cost effective supersonic ejector system packaging that is manufactured from a unitary housing, casing, or metal block.